What gave green lantern's power?

Answer 1

Each Green Lantern wields a Power_ring_(DC_Comics) that can generate a variety of effects, sustained purely by the ring wearer's imagination and strength of will. The greater the user's willpower, the more effective the ring. The upper limits of the power ring's abilities remain undefined, and it has been referred to as "the most powerful weapon in the universe" on more than one occasion. The Weaponers of Qward say that every weapon has a weakness and the weakness of a green lantern power ring is its wearer (though some argue that this is its strength). Across the years, the rings have been shown capable of accomplishing almost anything within the imagination of the ring bearer. Stories in 2006 Retconthe ring's long-established ineffectiveness on yellow objects, stating that the ring-wielder need only feel fear, understand it and overcome it in order to affect yellow objects (however, it is a learned and practiced ability, making it a weakness to some Green Lanterns), giving retroactive credence to the explanation of the ring's real but surmountable weakness to yellow.

Power rings as used by various wielders, have exhibited (but are not limited to)